50/50 split might be naive. It assumes men and women should be equally represented and that makes liberally minded folks feel good. But what's the alternative? Status quo? A different and arbitrary split? I don't see any good arguments against equal representation.

The current diversity initiative is biasing towards 50/50 and the memo guy didn't like it but didn't suggest what it should be, only that it should be less because biology. You can see why some people might read that as a first step back to status quo.

Personally, I feel 50/50 is a good first approximation. Maybe it's really 70/30, but no one knows and there aren't any studies to back any up.

Oh wait there is: Bear, Julia B., and Anita Williams Woolley. "The role of gender in team collaboration and performance." Interdisciplinary science reviews 36.2 (2011): 146-153.